source/unres/src_MD/src/md-diff/mts/verlet1.f

   1 c-----------------------------------------------------------------
   2       subroutine verlet1
   3 c Applying velocity Verlet algorithm - step 1 to coordinates
   4       implicit real*8 (a-h,o-z)
   5       include 'DIMENSIONS'
   6       include 'COMMON.CONTROL'
   7       include 'COMMON.VAR'
   8       include 'COMMON.MD'
   9       include 'COMMON.CHAIN'
  10       include 'COMMON.DERIV'
  11       include 'COMMON.GEO'
  12       include 'COMMON.LOCAL'
  13       include 'COMMON.INTERACT'
  14       include 'COMMON.IOUNITS'
  15       include 'COMMON.NAMES'
  16       double precision adt,adt2
  17
  18 #ifdef DEBUG
  19       write (iout,*) "VELVERLET1 START: DC"
  20       do i=0,nres
  21         write (iout,'(i3,3f10.5,5x,3f10.5)') i,(dc(j,i),j=1,3),
  22      &   (dc(j,i+nres),j=1,3)
  23       enddo
  24 #endif
  25       do j=1,3
  26         adt=d_a_old(j,0)*d_time
  27         adt2=0.5d0*adt
  28         dc(j,0)=dc_old(j,0)+(d_t_old(j,0)+adt2)*d_time
  29         d_t_new(j,0)=d_t_old(j,0)+adt2
  30         d_t(j,0)=d_t_old(j,0)+adt
  31       enddo
  32       do i=nnt,nct-1
  33         do j=1,3
  34           adt=d_a_old(j,i)*d_time
  35           adt2=0.5d0*adt
  36           dc(j,i)=dc_old(j,i)+(d_t_old(j,i)+adt2)*d_time
  37           d_t_new(j,i)=d_t_old(j,i)+adt2
  38           d_t(j,i)=d_t_old(j,i)+adt
  39         enddo
  40       enddo
  41       do i=nnt,nct
  42         if (itype(i).ne.10) then
  43           inres=i+nres
  44           do j=1,3
  45             adt=d_a_old(j,inres)*d_time
  46             adt2=0.5d0*adt
  47             dc(j,inres)=dc_old(j,inres)+(d_t_old(j,inres)+adt2)*d_time
  48             d_t_new(j,inres)=d_t_old(j,inres)+adt2
  49             d_t(j,inres)=d_t_old(j,inres)+adt
  50           enddo
  51         endif
  52       enddo
  53 #ifdef DEBUG
  54       write (iout,*) "VELVERLET1 END: DC"
  55       do i=0,nres
  56         write (iout,'(i3,3f10.5,5x,3f10.5)') i,(dc(j,i),j=1,3),
  57      &   (dc(j,i+nres),j=1,3)
  58       enddo
  59 #endif
  60       return
  61       end